1. Field of the Invention
The present invention relates to a tape rule with an elaborate buffer, and more particularly, to a tape rule buffer which alleviates and absorbs backlashing force of the tape during its retraction thereby protecting the tape hook from being damaged or deformed, and ensuring accuracy and durability of the tape rule.
2. Description of the Prior Art
As it is known, most of conventional tape rules are not provided with any buffering device. Therefore, a tape hook equipped on the tip of the tape is prone to be damaged or deformed, or even the tape is torn near the tape hook by a sudden uncontrolled backlashing force caused by the retraction of the tape rendering the tape rule useless. Such phenomenon degrades a conventional tape rule's accuracy of measurement, or even shortens the lifetime of the tape rule which insures the user's unwilling early replacement of his old tape rule with a new one.
To solve this shortcoming, several trials were made for improvement. For example, U.S. Pat. No. 5,395,069 and No. 4,748,746, both show a longitudinally laid arc-shaped counteract region provided either at the outlet or at the rear part of the tape.
In another case patented by U.S. Pat. No. 5,791,581, there is a buffering member provided at the passage of the tape retraction route of a tape rule in which comprises a flat plate at its front end for catching the impact of the retracting tape and transmitting it to a compressed spring provided at the rear end of the buffering member and secured to the flat plate with a prong such that the retracting force of the tape may be absorbed by the spring thereby preventing possible damage to the tape rule. However, the structure is complex and the buffering member is separately assembled which results in increasing production cost. It is also difficult to ensure the quality of the product in case the assembly work is not properly carried out. Thus, it is impossible to ensure a perfect buffering effect and a minimum fault rate of the tape rule. In addition, both buffering member and compressed spring are made of pressed or flexed thin metal strip liable to depart from their original position or even fall off.
In order to solve the problems mentioned above, research and development efforts have been carried out by the inventor of the present invention and finally succeeded in providing a tape rule with an elaborate buffer which is to be disclosed hereinafter.